This invention concerns water-dispersible binders and the incorporation of such binders in products used to retain fluids exuded from the body such as blood, menstrual fluid and urine. Specifically, the binders and nonwoven fabrics of this invention are useful in connection with absorbent products such as sanitary napkins, diapers, dressings and the like. The fabrics of this invention exhibit adequate tensile strength and retain their structural integrity when in contact with the aforesaid body fluids, yet are readily dispersible in water or aqueous solutions of relatively low ionic strength so that the absorbent product may be flushed away after use.
Nonwoven fabrics are widely used as components of such disposable goods as sanitary napkins, diapers, bandages, and the like. Such fabrics, if they are to function effectively, must maintain their structural integrity, as well as exhibit satisfactory tensile strength, when they are wet or damp with the various body fluids, for example, blood, menstrual fluid and urine, with which they come into contact during use. It has been recognized that if such nonwoven fabrics, while retaining their strength in body fluids, were to lose substantially all their tensile strength when exposed to water and become readily dispersible therein, disposal problems would be substantially eliminated since the fabrics could be easily and conveniently flushed away in a water closet.
Unfortunately, in an attempt to provide nonwoven fabrics having certain desirable in-use characteristics, prior methods have rendered the fabric nondispersible in water. For example, nonwovens have been bonded with body fluid-insoluble resins which impart in-use strength. Generally, however, such resins have been water-insoluble as well and have impeded disposal of the fabric by flushing. Therefore, less desirable methods of disposal such as incineration or dumping must be employed.
Heretofore, the choice of suitable binders for water-dispersible products has been extremely limited in that the properties of binders to impart to fabrics both the characteristics of satisfactory in-use strength and water-dispersibility are infrequently found in combination. For example, the binder must impart sufficient strength for the fabric to resist disintegration for a reasonable period of time when the nonwoven fabric is in use, i.e., the binder must be insoluble or at least only slightly soluble in body fluids and must exhibit substantial tensile strength when subjected to such fluids. In addition, a suitable binder must provide the fabric with sufficient abrasive strength to withstand wear and tear when the product is one which is to be worn, such as a dressing, a sanitary napkin or a diaper. In apparent conflict with these properties, the binder must allow the fabric to be readily dispersed in water so that the absorbent product can be conveniently flushed away after use and also insure that the fabric is soft and flexible so as to be comfortable to the user. These criteria are difficult to meet with a single material, and hence, a choice of binders, suitably possessing both properties, has heretofore been extremely limited.